Using bash shell from within PHP

Question

In my terminal window (using Max OS X) my shell is bash. However when I run a command in PHP via shell_exec or backtick operators I see that PHP is using the Bourne Shell (sh). Here's an example of what I'm seeing:

From within my terminal window:

$ echo $0
- bash

Also if I call php as follows:

$ php -r "echo shell_exec('echo $0');"
-bash

However, if I create a script called test.php with the following:

<?php echo shell_exec('echo $0'); ?>

And then run test php I get the following:

$ php test.php
sh

I'm wanting to use the bash shell when calling shell_exec - why is it choosing the Bourne shell and can I force it to use bash?

Thanks!

Dan

Answer 1

Reverse the quotes in your second command:

$ php -r 'echo shell_exec("echo $0");'
sh

With the quotes as you had them in your question, the variable $0 is expanded before the command is sent to php.

If you want to force the use of Bash, you could do something like:

php -r '$cmd="echo \\\$0"; echo shell_exec("/bin/bash -c \"$cmd\"");'

Answer 2

Assuming that:

1. your PHP script is executed by the web server (say, Apache)
2. the web server is executed with the rights of a special user account,

one of the possible (but not optimal) solutions would be to change the default shell of the user account under which your web server is executed.

Answer 3

It probably reads the SHELL environment variable. Disregard that, putenv() didn't work.

Try to just run the command you want with bash, like

shell_exec("bash script.sh");